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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 39, Issue 12 - Dec 2015
Volume 39, Issue 11 - Nov 2015
Volume 39, Issue 10 - Oct 2015
Volume 39, Issue 9 - Sep 2015
Volume 39, Issue 8 - Aug 2015
Volume 39, Issue 7 - Jul 2015
Volume 39, Issue 6 - Jun 2015
Volume 39, Issue 5 - May 2015
Volume 39, Issue 4 - Apr 2015
Volume 39, Issue 3 - Mar 2015
Volume 39, Issue 2 - Feb 2015
Volume 39, Issue 1 - Jan 2015
Selecting the target year
Determining Mechanical Properties of ZrO
Composite Ceramics by Weibull Statistical Analysis
Kim, Seon Jin ; Kim, Dae Sik ; Nam, Ki Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 955~962
DOI : 10.3795/KSME-A.2015.39.10.955
The Vickers test can be used for all types of materials, and it has one of the widest scales among hardness tests. The hardness may be considered as a probability variable when evaluating the mechanical properties of materials. In this study, we investigate the statistical properties of the bending strength and Vickers hardness in
composites depending on the amount of
additives. The bending strength and Vickers hardness were found to agree well with the Weibull probability distribution. We evaluate the scale parameter and shape parameter in as-received
ceramics, as well as their heat treated ceramics. We also evaluate the parameters in accordance with the increase in in the indentation load.
Finite Element Analysis of Large Deformation of Fiber Metal Laminates Under Bending for Stress-Strain Prediction
Yeom, Kyung Mi ; Lee, Jongsoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 963~970
DOI : 10.3795/KSME-A.2015.39.10.963
Laminate structures are used in the automobile, aerospace, and display industries. The advantages of fiber metal laminates are well known. Fiber metal laminates are useful for reducing the weight and improving impact resistance . However, currently, the mechanical properties of fiber metal laminates are not derived. In this paper, we use thickness as a factor for comparing the properties of laminates of various thickness combinations. The properties fiber metal laminates are analyzed using design of experiments. In addition, the finite element method is used to analyze elastic and plastic strains of fiber metal laminates and aluminum plates. The final goal of this paper is to find a suitable finite element model of fiber metal laminates under bending.
A Study on Fracture Characteristic of Aluminum Foam by Thickness
Gao, Teng ; Cho, Jae Ung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 971~977
DOI : 10.3795/KSME-A.2015.39.10.971
Because foam metal has the excellent physical characteristics and mechanical performance, they are applied extensively into a lot of advanced technology areas. The aluminum foam with closed cell is one of the foam metals. It is applied widely into automobile and airplane because of the excellent absorption performance of impact energy. In this study, the mechanical characteristics by thickness was analyzed through the impact experiment of closed-cell aluminum foam, and the simulation analysis was performed for the verification. As the simulation analysis method, a finite-element analysis was carried under the same boundary conditions as the experiment by using ANSYS. By comparing with the results of experiment and simulation, it was thought that the case of thickness of 20mm was the most efficient of among the cases of thicknesses of 10mm, 20mm and 30mm. At the case of thickness of 20mm, the absorption energy by comparing with the specimen thickness is shown to become the most among three models. By using the result of this study, it is thought that it can apply the material necessary to develop the mechanical structure with aluminum foam.
Stress Distributions at the Dissimilar Metal Weld of Safety Injection Nozzles According to Safe-end Length and SMW Thickness
Kim, Tae-Jin ; Jeong, Woo-Chul ; Huh, Nam-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 979~984
DOI : 10.3795/KSME-A.2015.39.10.979
In the present paper, we evaluate the effects of the safe-end length and thickness of the similar metal weld (SMW) of safety injection nozzles on stress distributions at the dissimilar metal weld (DMW). For this evaluation, we carry out detailed 2-D axisymmetric finite element analyses by considering four different values of the safe-end length and four different values of the thickness of SMW. Based on the results obtained, we found that the SMW thickness affects the axial stresses at the center of the DMW for the shorter safe-end length; on the other hand, it does not affect the hoop stresses. In terms of the safe-end length, the values of the axial and hoop stresses at the inner surface of the DMW center increase as the safe-end length increases. In particular, for the cases considered in the present study, the stress distributions at the DMW center can be categorized according to certain values of safe-end length.
Dynamic Model Prediction and Validation for Free-Piston Stirling Engines Considering Nonlinear Load Damping
Sim, Kyuho ; Kim, Dong-Jun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 985~993
DOI : 10.3795/KSME-A.2015.39.10.985
Free-piston Stirling engines (FPSEs) have attracted much attention in the renewable energy field as a key device in the conversion from thermal to mechanical energy, and in the recycling of waste energy. Traditional Stirling engines consist of two pistons that are connected by a mechanical link, while FPSEs are formed as a vibration system by connecting each piston to a spring without a physical link. To ensure the correct design and control of operations, this requires elaborate dynamic-performance predictions. In this paper, we present the performance-prediction methodology using a linear and nonlinear dynamic analytical model considering the external load of FPSEs. We perform linear analyses to predict the operating point of the engine using the root locus technique. Using nonlinear analysis, we also predict the amplitude of pistons by performing numerical integration considering both the linear and nonlinear damping terms of the external load. We utilize the predicted dynamic behavior to predict the engine performance. In addition, we compare the experiment results and existing model predictions for RE-1000 to verify the reliability of the analytical model.
Ring-Shaped Inductive Sensor Design and Application to Pressure Sensing
Noh, Myounggyu ; Kim, Sunyoung ; Baek, Seongki ; Park, Young-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 995~999
DOI : 10.3795/KSME-A.2015.39.10.995
Inductive sensors are versatile and economical devices that are widely used to measure a wide variety of physical variables, such as displacement, force, and pressure. In this paper, we propose a simple inductive sensor consisting of a thin partial ring and a coil set. The self-inductance of the sensor was estimated using magnetic circuit analysis and validated through finite element analysis (FEA). The natural frequency of the ring was estimated using Castigliano's theorem and the method of equivalent mass. The estimation was validated through experiments and FEA. A prototype sensor with a signal processing circuit is built and applied to noninvasively sense the pressure inside a flexible tube. The obtained sensor outputs show quadratic behavior with respect to the pressure. When fitted to a quadratic equation, the least-square measurement error was less than 2%. The results confirm the feasibility of pressure sensing using the proposed inductive sensor.
Estimation of Transient Creep Crack-tip Stress Fields for SE(B) specimen under Elastic-Plastic-Creep Conditions
Lee, Han-Sang ; Je, Jin-Ho ; Kim, Dong-Jun ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1001~1010
DOI : 10.3795/KSME-A.2015.39.10.1001
This paper estimates the time-dependent crack-tip stress fields under elastic-plastic-creep conditions. We perform Finite-Element (FE) transient creep analyses for a Single-Edge-notched-Bend (SEB) specimen. We investigate the effect of the initial plasticity on the transient creep by systematically varying the magnitude of the initial step-load. We consider both the same stress exponent and different stress exponent in the power-law creep and plasticity to determine the elastic-plastic-creep behaviour. To estimation of the crack-tip stress fields, we compare FE analysis results with those obtained numerically formulas. In addition, we propose a new equation to predict the crack-tip stress fields when the creep exponent is different from the plastic exponent.
Numerical Thermal Analysis of IGBT Module Package for Electronic Locomotive Power-Control Unit
Suh, Il Woong ; Lee, Young-ho ; Kim, Young-hoon ; Choa, Sung-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1011~1019
DOI : 10.3795/KSME-A.2015.39.10.1011
Insulated-gate bipolar transistors (IGBTs) are the predominantly used power semiconductors for high-current applications, and are used in trains, airplanes, electrical, and hybrid vehicles. IGBT power modules generate a considerable amount of heat from the dissipation of electric power. This heat generation causes several reliability problems and deteriorates the performances of the IGBT devices. Therefore, thermal management is critical for IGBT modules. In particular, realizing a proper thermal design for which the device temperature does not exceed a specified limit has been a key factor in developing IGBT modules. In this study, we investigate the thermal behavior of the 1200 A, 3.3 kV IGBT module package using finite-element numerical simulation. In order to minimize the temperature of IGBT devices, we analyze the effects of various packaging materials and different thickness values on the thermal characteristics of IGBT modules, and we also perform a design-of-experiment (DOE) optimization
Design and Analysis of Shell Runners to Improve Cooling Efficiency in Injection Molding of Subminiature Lens
Yoon, Seung Tak ; Park, Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1021~1028
DOI : 10.3795/KSME-A.2015.39.10.1021
Subminiature lenses are currently widely used in mobile phone cameras and are usually produced by injection molding. The lens molding process has the unique feature of a runner volume that is much larger than the part volume, and this feature should be considered when determining the mold design and molding conditions. In this study, a shell-type runner was proposed as an alternative to the conventional cylindrical runner used for lens molding. An injection molding simulation was performed by applying the proposed shell runner, and the simulation results were compared with those from the cylindrical runner case. It was found that the shell runner could considerably reduce the runner cooling time with only a slight increase in the injection pressure. The effect of the runner thickness was then investigated numerically in terms of the mold filling and cooling characteristics, from which an optimal runner thickness could be determined.
Identification of Frequency-Dependent Dynamic Characteristics of a Bump Structure for Gas-Foil Bearings via 1-DOF Shaker Tests Under Air Pressurization
Sim, Kyuho ; Park, Jisu ; Lee, Sanghun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1029~1037
DOI : 10.3795/KSME-A.2015.39.10.1029
Recently, the importance of rotordynamic stability has been increased because of the tendency to employ ultra-high speeds in rotating machinery. In particular, the dynamic characteristics of gas bearings for high-speed rotating machinery need to be identified at various excitation frequencies to predict the rotor's behavior. In this study, we perform dynamic loading tests for gas-foil bearings (GFBs) to determine the bump foil structure and an air-film combined bump-foil structure for varying excitation frequencies. We calculate the dynamic characteristics from the measured force and displacement data. The air film is generated by a pressurized air supply. Based on the results, the stiffness coefficients of the bump structure and the air-film combined bump structure increased, while the damping coefficients decreased at increasing excitation frequencies. Further, the stiffness and damping coefficients of the air-film combined structure show lower values than those of the bump structure. Consequently, we identify the frequency-dependent dynamic characteristics of the bump structure and the effect of gas film on the dynamic characteristics of GFBs. Furthermore, to reveal the effectiveness of the proposed method, we perform experiments and discuss two methods of extracting the dynamic characteristics from the measured data.
Fatigue Analysis of Rear Suspension Part Applying Multi-body Dynamics
Jeon, Seong Min ; Cho, Byung-Kwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1039~1044
DOI : 10.3795/KSME-A.2015.39.10.1039
During the development of vehicles, durability tests are time consuming and costly. Recently, automobile companies have attempted to develop their own durability evaluation procedures by modifying and complementing . In this paper, we propose an integrated computer-aided engineering (CAE) method to evaluate the durability of a torsion beam axle (TBA). We compare this method with the standardized durability evaluation method used by an actual automobile company in order to determine the feasibility of this method. We compare the results with the test result data to enable us to estimate the reliability of the analysis results. In this study, we analyze the processes and results of the quasi-static fatigue analysis, and found improved methods and problems. Furthermore, we perform a thorough test using the requirements of the actual company. Based on the results, the structural analysis process in the quasi-static fatigue analysis method was superseded by the multi-body dynamics analysis process. Generally, this method is referred to as the resonance-fatigue analysis method.
Stabilization Design of Large Rotating Stand Using Sliding Mode Control
Kim, Sungryong ; Park, Dongmyung ; Moon, Wooyong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1045~1052
DOI : 10.3795/KSME-A.2015.39.10.1045
In this paper, a stabilized control algorithm for the large rotating stand of a long-range surveillance radar (LRSR) system is introduced. The stabilized control algorithm for this large rotating stand system was designed using mathematical plant modeling. The LRSR system is located on high ground and has a wide surface, making it susceptible to the effects of wind, which increases the bearing friction and reduces the stability of the rotating stand. The disturbance caused by the wind was analyzed using computational fluid dynamics (CFD) in this study. The results of the CFD analysis were used to construct a control algorithm for the disturbance . The performance of the proposed control algorithm was demonstrated experimentally and through simulations. The plant model and the control algorithm were constructed in Matlab/Simulink.
Deformation Behavior of Curling Strips on Tearing Tubes
Choi, Ji Won ; Kwon, Tae Soo ; Jung, Hyun Seung ; Kim, Jin Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1053~1061
DOI : 10.3795/KSME-A.2015.39.10.1053
This paper discusses the analysis of the curl deformation behavior when a dynamic force is applied to a tearing tube installed on a flat die to predict the energy absorption capacity and deformation behavior. The deformation of the tips of the curling strips was obtained when the curl tips and tube body are in contact with each other, and a formula describing the energy dissipation rate caused by the deformation of the curl tips is proposed. To improve this formula, we focused on the variation of the curl radius and the reduced thickness of the tube. A formula describing the mean curl radius is proposed and verified using the curl radius measurement data of collision test specimens. These improved formulas are added to the theoretical model previously proposed by Huang et al. and verified from the collision test results of a tearing tube.
Study on 3-D Simulation for Overriding Evaluation of Urban Train
Jin, Sung Zu ; Jung, Hyun Seung ; Kwon, Tae Soo ; Kim, Jin Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1063~1068
DOI : 10.3795/KSME-A.2015.39.10.1063
In this paper, we propose a collision simulation technique the evaluation of urban trains. We perform simulation that include a dynamics bogie model which represents the dynamic behavior of bogies and a finite-element model that can model crash behavior. We perform simulation in accordance with the 40-mm vertical offset head-on scenario for overriding the evaluation of the EU and domestic crashworthiness regulations. We evaluate the overriding by the vertical displacement of the wheelset using the overriding evaluation standard. Finally, if proposed simulation technique is applied, we can evaluate the overriding for urban-train crashworthiness regulations.
Study on a Wire Saw Rock Cutting Model for Tunnel Excavation and Cutting Performance Improvement
Lee, Jin-Ho ; Ahn, Sung-Kwon ; Lee, Kyoung-Chan ; Bang, Choon-Seok ; Sagong, Myung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 10, 2015, Pages 1069~1077
DOI : 10.3795/KSME-A.2015.39.10.1069
In tunnel excavation using blast, the wire saw rock cutting method generates a discontinuity perimeter around the center cut, and thus prevents blast vibration propagation to reduce vibration and noise. Therefore, the method is expected to be easy to use and economical compared with other methods. In this paper, the cutting mechanism of wire saw in tunnel excavation is investigated. A model describing the changes in cutting depth and wire saw shape inside a rock during cutting is established and validated for this purpose. Through a simulation using the model, the important characteristics of wire saw cut are investigated, and the influences of cutting conditions, such as wire saw tension, wire saw speed, feed speed, depth, and diameter of boring, on cutting performance are also examined. A method to improve the cutting performance is proposed based on the results.